In 1904, some remarkable elephant fossils were unearthed on Cape Malekas on the island of Crete by Dorothea Bate, a famous fossil hunter. Some of these fossils appeared to be from a mammoth, a group of elephants that are distinct from those we now know. Mammoths differ from the other elephants in a number of ways, such as having long and gracefully curved tusks instead of straight tusks and a domed skull instead of a flat head.

But for many years, all dwarf elephant fossils found on Mediterranean islands, including these from Crete, were thought to be descendants of the mainland straight-tusked elephant, Palaeoloxodon antiquus. Indeed, this European elephant was the ancestor of nearly all other extinct dwarf elephants found on a number of Mediterranean islands including Sicily, Malta and Cyprus. But not everyone in the scientific community was convinced that the Bate fossils were from Palaeoloxodon elephants.

Fossil elephant researcher, Victoria Herridge, at the Natural History Museum in London, wanted to learn more about the elephant fossils found on Crete, so she followed the pathway described in the Bate field notebooks and found the original coastal cliff on Crete's Cape Malekas where Bate found her fossils. Some of these fossils were exposed and included "[m]ultiple disarticulated bone and tooth fragments", writes Dr Herridge and her co-author, Adrian M. Lister, in their newly-published paper.

And as Dr Herridge suspected, this treasure trove of fossils contained the remains of a mammoth, Mammuthus creticus -- the smallest mammoth yet identified. But how did Drs Herridge & Lister determine that these fossils were from a mammoth and not an elephant? This tooth was key (figure 1b): as teeth wear down during an animal's life, the surface develops characteristic enamel 'rings'. Mammoth teeth differ from elephant teeth by having three oval rings (see "x" and "y" on figure 1b) instead of the one oval ring seen on elephant teeth:

The structure of the fossil tooth not only shows that it came from a Mammuthus, but it is most similar to earlier mammoth taxa; most likely M. meridionalis or possibly M. rumanus, rather than the more derived M. trogontherii.

M. meridionalis lived in Europe from 2.5 million to 800,000 years ago.

"But we couldn't rule out another species, M. rumanus," explains Dr Herridge. "M. rumanus is the earliest species of mammoth found in Europe (as long ago as 3.5 million years). This means the ancestor of M. creticus could have reached Crete as long ago as 3.5 million years."

Even though the diminutive size of the fossil teeth gave the team a rough idea of the size of the mammoth, the team found a fossil humerus (upper arm) bone that provided concrete evidence as to this mammoth's small size. The bone was completely fused, meaning that growth had stopped, so the team knew this bone came from an adult animal. By measuring this bone (figure 1f) and extrapolating from there, the team found that this particular adult mammoth was just 1.1m tall -- roughly the size of a modern baby African or Asian elephant:

Based on size, they estimated that the adult weighed about 300kg -- half the weight of the previously known smallest dwarf mammoth, M. lamarmorai.

Although they didn't test fossil dates in this research, the team's findings suggest M. creticus may have been on Crete longer than previously thought.

"I hadn't previously considered M. rumanus as a plausible ancestor because it was so old, geologically speaking, and so the evidence here has reminded me it doesn't do well to make assumptions in science!" Dr Herridge explained.

"In fact, this has now got us wondering about how long ago M. creticus arrived on Crete. Perhaps it got there much earlier than people generally think."

In this video, Dr Herridge shows us the fossils that led to her discovery: